Passenger&#39;s weight measurement device for vehicle seat

ABSTRACT

An upper rail is movable in a rear and front direction with respect to a lower rail fixed to a vehicle floor. A load sensor is fixed to an upper surface of the upper rail, and a rectangular frame  30  is attached onto the load sensor. A rod of the load sensor sequentially penetrates a web of the rectangular frame, a plain washer and a spring holder upward, and a coil spring is wound around the rod. A bush is fitted to an edge of a hole of the plain washer, and a step difference is formed between an upper surface of the plain washer and the bush. A nut is screwed to the rod, and the nut tightens a bottom of a cup portion of the spring holder. In such a way, the coil spring is sandwiched between the spring holder and the web and is compressed, and an end portion of the coil spring engages with the step difference.

This is a Continuation of application Ser. No. 11/992,418 filed Mar. 21, 2008, which in turn is a National Stage of PCT/JP2006/319479 filed Sep. 29, 2006, which in turn claims the benefit of Japanese Application No. 2005-286881 filed Sep. 30, 2005. The disclosures of the prior applications are hereby incorporated by reference herein in their entirety.

TECHNICAL FIELD

The present invention relates to a passenger's weight measurement device for a vehicle seat, which measures a weight of a passenger seated on the vehicle seat, and to an attachment structure for attaching a load sensor to the passenger's weight measurement device.

BACKGROUND ART

In recent years, in some cases, operations of various safety devices such as a seat belt and an air bag have been controlled in accordance with a weight of a passenger seated on a vehicle seat for the purpose of enhancing performance of the safety devices. In a conventional passenger's weight measurement device that measures the weight of the seated passenger, a load sensor is interposed between a vehicle floor and the vehicle seat (for example, refer to Patent Document 1 and Patent Document 2).

-   Patent Document 1: JP A H8-164039 -   Patent Document 2: JP A H9-207638

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention

However, there is a dimension error or an assembling position error when the passenger's weight measurement device is assembled, when the vehicle seat is fixed to the passenger's weight measurement device or when the passenger's weight measurement device is fixed to the vehicle floor, or the like. Accordingly, it has been difficult to assemble the passenger's weight measurement device.

In this connection, it is an object of the present invention to provide a passenger's weight measurement device for a vehicle seat, which is more easily assembled.

Means for Solving the Problems

In order to solve the above-described problem, a passenger's weight measurement device for a vehicle seat according to the present invention comprises: an upper rail provided on a lower rail fixed to a vehicle floor so as to be movable in a rear and front direction; a load sensor fixed onto the upper rail; and a frame provided on the load sensor and below the vehicle seat, wherein a rod is extended from the load sensor, and the rod sequentially penetrates the frame, a plain washer and a spring holder, and is inserted into a coil spring, a bush is disposed along an edge of a hole of the plain washer, though which the rod is inserted, and a step difference is formed between an upper surface of the plain washer and the bush by protruding the bush from the upper surface, and a nut is screwed to the rod from above the spring holder, and the coil spring is sandwiched between the spring holder and the frame and is compressed and an end portion of the coil spring engages with the step difference by tightening the nut to the spring holder.

Effect of the Invention

In accordance with the present invention, the frame can be shifted in the vertical direction with respect to the load sensor. Accordingly, even if the lower rail, the upper rail, the frame and the like are distorted during the assembling or the like, an initial load generated by such distortions can be prevented from being applied to the load sensor.

Moreover, the coil spring is sandwiched between the frame and the spring holder in a state of being compressed by tightening the nut. Accordingly, the load sensor is fixed to the frame more stably and appropriately. Therefore, it becomes easier to assemble the passenger's weight measurement device.

Furthermore, the load is stably applied from the coil spring to the nut owing to elastic deformation of the coil spring, which is caused by tightening the nut.

Moreover, by tightening the nut, the end portion of the coil spring engages with the step difference formed between the upper surface of the washer and the bush. Accordingly, the coil spring is centered with respect to the washer without slipping on the upper surface of the washer.

BRIEF DESCRIPTION OF THE DRAWINGS

[FIG. 1] This is a perspective diagram of a passenger's weight measurement device 1 for a vehicle seat.

[FIG. 2] This is an exploded perspective diagram of the passenger's weight measurement device 1.

[FIG. 3] This is a perspective diagram of a load sensor 21.

[FIG. 4] This is a plan diagram of a rectangular frame 30.

[FIG. 5] This is a plan diagram of a right front portion of the rectangular frame 30.

[FIG. 6] This is a cross-sectional diagram showing a cross section along a line VI-VI of FIG. 5.

[FIG. 7] This is a cross-sectional diagram showing a cross section along a line VII-VII of FIG. 5.

BEST MODE FOR CARRYING OUT THE INVENTION

A best mode for carrying out the present invention will be described below by using the drawings. On embodiments to be described below, a variety of technically preferable limitations are imposed in order to carry out the present invention; however, the scope of the invention is not limited to the following embodiment and illustrated examples.

FIG. 1 is a perspective diagram of a passenger's weight measurement device 1 for a vehicle seat, and FIG. 2 is an exploded perspective diagram of the passenger's weight measurement device 1.

As shown in FIG. 1 and FIG. 2, a slide adjuster 2 for adjusting a back-and-forth position of the vehicle seat is attached onto a floor of a passenger's room. The slide adjuster 2 includes a left and right pair of lower rails 3 provided in parallel to each other, a left and right pair of upper rails 4 engaged with the lower rails 3 so as to be capable of sliding on the respective lower rails 3 in a rear and front direction with respect to the lower rails 3, a lower bracket 5 fixed to lower surfaces of the lower rails 3 by bolt/nut coupling or rivet coupling and bridged between the left and right lower rails 3, a lock mechanism 6 for locking the upper rails 4 to the lower rails 3 and for releasing the locking, brackets 7 attached onto front end portions of the lower surfaces of the respective lower rails 3, and brackets 8 attached onto rear end portions of the lower surfaces of the respective lower rails 3. These brackets 7 and 8 are attached onto the vehicle floor, and the lower rails 3 are fixed to the vehicle floor.

Brackets 9 are fixed to middle positions of upper surfaces of the respective upper rails 4 in a rear and front direction by the bolt/nut coupling or the rivet coupling. The brackets 9 are provided in a state of being erected with respect to upper surfaces of the upper rails 4. A right end portion of a submarine pipe 10 is welded to the brackets 9, and the submarine pipe 10 is bridged between the two left and right brackets 9.

A load sensor 21 is mounted on a front end portion of the upper surface of the right upper rail 4, and another load sensor 21 is mounted on a rear end portion thereof. Also on the upper surface of the left upper rail 4, load sensors 21 are mounted on a front end portion and rear end portion thereof, respectively. When viewed from the above, these four load sensors 21 are arranged so as to be apexes of a square or a rectangle.

FIG. 3 is a perspective diagram of the load sensor 21. All of the load sensors 21 are provided in a similar way. As shown in FIG. 3, the load sensor 21 includes a columnar sensing portion 21 a that senses a load, a plate-like flange portion 21 b extending horizontally in a rear and front direction from a lower end of the sensing portion 21 a, a rod 21 c extending upward from an upper end of the sensing portion 21 a, and a connector 21 d extending from the sensing portion 21 a so as to be parallel to the flange portion 21 b. The rod 21 c is formed into a male screw shape. Female screw-shaped circular holes 21 e and 21 f which penetrate the flange portion 21 b in the vertical direction are formed in front and rear portions of the flange portion 21 b, respectively. The sensing portion 21 a incorporates a strain gauge therein, and the load is converted into an electric signal by the strain gauge.

As shown in FIG. 2, the load sensor 21 is fixed to the right upper rail 4. Specifically, a lower surface of the flange portion 21 b abuts on the upper surface of the upper rail 4, and two bolts 22 inserted through the upper rail 4 upward from below are screwed to the circular holes 21 e and 21 f, respectively. Therefore, the load sensor 21 is fixed. Note that the load sensor 21 may be fixed to the upper rail 4 by fastening nuts to the bolts 22 on the flange portion 21 b without forming any screw threads in the circular holes 21 e and 21 f.

Any load sensor 21 is fixed to the upper rails 4 as described above. However, with regard to the two load sensors 21 fixed to the rear portions thereof, the connectors 21 d are directed forward, and with regard to the two load sensors 21 fixed to the front portions thereof, the connectors 21 d are directed backward.

As shown in FIG. 1 and FIG. 2, the frame 30 having a rectangular frame shape is mounted on these four load sensors 21. FIG. 4 is a top diagram of the rectangular frame 30. As shown in FIG. 4, the rectangular frame 30 is composed of a left and right pair of beams 31, a front beam 32, and a rear cross pipe 33.

Either of the beams 31 is a metal member having a U-shaped cross section, and has a web 31 a, an inner flange 31 b, and an outer flange 31 c. Attachment holes 31 d are formed in a front portion and a rear portion of the web 31 a, respectively.

The front beam 32 is a metal member having a U-shaped cross section, and has a web 32 a, a front flange 32 b, and a rear flange 32 c. The front beam 32 is bridged between front end portions of the left and right beams 31, and is welded to these beams 31.

The cross pipe 33 is bridged between rear end portions of the left and right beams 31, and is welded to these beams 31.

The rods 21 c of the load sensors 21 are inserted into the respective attachment holes 21 d upward from below, and nuts 46 are screwed to the rods 21 c. Therefore, the load sensors 21 are attached onto a right front portion, a right rear portion, a left front portion and a left rear portion of the rectangular frame 30, respectively. Referring to FIG. 5 to FIG. 7, an attachment structure for attaching the right front load sensor 21 onto the right front portion of the rectangular frame 30 will be described. FIG. 5 is a plan diagram of the right front portion of the rectangular frame 30, FIG. 6 is a cross-sectional diagram showing a cross section along a line VI-VI, and FIG. 7 is a cross-sectional diagram showing a cross section along a line VII-VII. As shown in FIG. 5 to FIG. 7, an annular bush 41 is fitted to an edge of the right front attachment hole 31 d, and grease is applied on the bush 41. The bush 41 is made of synthetic resin. Moreover, a stepped collar 42 composed of a cylindrical portion 42 a and an annular plate-like flange portion 42 b formed on one end surface of the cylindrical portion 42 a is inserted through the attachment hole 31 d in an inside of the bush 41. Here, the cylindrical portion 42 a is inserted through the attachment hole 31 d upward from below, and the flange portion 42 b engages with a lower surface of the web 31 a via the bush 41. Therefore, the stepped collar 42 is not pulled out upward. Moreover, the cylindrical portion 42 a protrudes from an upper surface of the web 31 a, and an upper end surface of the cylindrical portion 42 a is located at a higher position than the upper surface of the web 31 a. Here, the cylindrical portion 42 a is fitted to the bush 41, and there is no gap between the cylindrical portion 42 a and the bush 41.

The rod 21 c of the load sensor 21 is inserted through the stepped collar 42 upward from below. An inner diameter of the stepped collar 42 is designed to be slightly larger than a diameter of the rod 21 c, and by such designing, a dimension error and an attachment position error are solved.

The nut 46 is screwed to the rod 21 c. A plain washer 43, a coil spring 44 and a spring holder 45 are interposed between the upper surface of the web 31 a of the beam 31 and the nut 46. An annular bush 43 a is disposed along an edge of a hole of the plain washer 43, and the edge of the hole of the plain washer 43 is sandwiched vertically by this bush. Therefore, the bush 43 a is fitted to the edge of the hole of the plain washer 43. In such a way, the bush 43 a and the plain washer 43 are integrated with each other. Moreover, the bush 43 a protrudes from an upper surface of the plain washer 43. Therefore, a step difference 43 b is formed on the upper surface of the plain washer 43 by the bush 43 a. Moreover, a lower surface of the plain washer 43 and a lower surface of the bush 43 a become flush with each other. Furthermore, the rod 21 c is inserted through the coil spring 44, the coil spring 44 is set in a state of being mounted on the plain washer 43 on a circumference of the bush 43 a, and an end portion of the coil spring 44 engages with the step difference 43 b formed by the bush 43 a. Therefore, the coil spring 44 is centered with respect to the plain washer 43. A portion of the coil spring 44, which is brought into contact with the plain washer 43, is formed to be flat. The bush 43 a is made of synthetic resin, and a tapping sound is prevented by the bush 43 a.

The spring holder 45 includes a cup portion 45 c in which a through hole is formed in a bottom 45 b, and an annular flange 45 a formed on an outer circumferential surface in an opening of the cup portion 45 c. Then, the rod 21 c penetrates through the through hole of the bottom 45 b of the cup portion 45 c, the bottom 45 b of the cup portion 45 c is set in a state of being mounted on an end surface of the stepped collar 42, and the cup portion 45 c is inserted into the coil spring 44. Moreover, the coil spring 44 and the plain washer 43 are set in a state of being sandwiched between the flange 45 a of the spring holder 45 and the web 31 a.

The nut 46 is screwed to the rod 21 c in a state of being inserted into the cup portion 45 c, and by tightening the nut 46, the bottom 45 b of the cup portion 45 c is sandwiched between the nut 46 and the upper end surface of the cylindrical portion 42 a, and the coil spring 44 and the plain washer 43 are sandwiched between the flange 45 a and the web 31 a of the beam 31. Moreover, since the coil spring 44 is compressed by tightening the nut 46, the load is applied to the nut 46, and accordingly, the nut 46 is prevented from being loosened.

Like the right front load sensor 21, the left front, left rear and right rear load sensors 21 are attached onto the left front, left rear and right rear attachment holes 31 d, respectively. In a state where the four load sensors 21 are attached onto the rectangular frame 30, the submarine pipe 10 is located behind the front beam 32.

As shown in FIG. 1 and FIG. 2, side frames 51 are welded to the outer flanges 31 c of the left and right beams 31, respectively. These side frames 51 are parts of a bottom frame of the vehicle seat.

From above, front portions of the side frames 51 are covered with a pan frame 53, and the side frames 51 and the pan frame 53 are fixed to each other by the bolt/nut coupling or the rivet coupling. A seat spring 54 is bridged between the cross pipe 33 and the pan frame 53, a cushion is mounted on the pan frame 53 and the seat spring 54, and the cushion, the pan frame 53 and the side frames 51 are entirely covered with a cover.

A backrest frame is coupled to rear ends of the side frames 51, and is capable of rising and falling by a reclining mechanism. Note that the backrest frame and the cushion are not shown in order to make it easy to view the drawings.

In the passenger's weight measurement device 1 configured as described above, when a passenger is seated on a seat bottom, a weight of the passenger is applied to the four load sensors 21 through the rectangular frame 30, and is converted into electric signals by these load sensors 21.

Here, the load sensors 21 are attached between the upper rails 4 and the rectangular frame 30, and the load sensors 21 move in a rear and front direction integrally with the vehicle seat. Accordingly, a load inputted from the vehicle seat to the load sensors 21 can be always kept constant irrespective of position of the vehicle seat in a rear and front direction. Therefore, measuring accuracy of the passenger's weight can be enhanced.

Moreover, the spring holder 45 is mounted on the upper end surface of the stepped collar 42, and the coil spring 44 is sandwiched between the spring holder 45 and the web 31 a by tightening the nut 46. Accordingly, the rectangular frame 30 can be shifted in the vertical direction with respect to the load sensors 21. Therefore, noise of the load generated by distortion of the slide adjuster 2 and the like becomes smaller.

Moreover, even if the rectangular frame 30 can be shifted in the vertical direction with respect to the load sensors 21, the coil springs 44 are interposed between the nuts 46 and the webs 31 a, and accordingly, the load sensors 21 can be fixed to the rectangular frame 30 more stably and appropriately. Therefore, it becomes easier to assemble the passenger's weight measurement device 1.

Moreover, the load is stably applied from each of the coil springs 44 to each of the nuts 46 owing to elastic deformation of the coil spring 44, which is caused by tightening the nut 46.

Moreover, the submarine pipe 10 is located behind the front beam 32, and accordingly, when forward inertial force is applied to the passenger owing to a frontal collision or the like of the vehicle, buttocks of the passenger seated on the vehicle seat are restrained by the submarine pipe 10. Therefore, a so-called submarine phenomenon in which the passenger moves under a waist belt can be prevented.

Note that the present invention is not limited to the above-described embodiment, and various improvements and design changes can be made within the scope without departing from the gist of the present invention.

INDUSTRIAL APPLICABILITY

As described above, the present invention can be widely used, for example, for seats of an automobile, an electric train and other vehicles. 

1. A passenger weight measurement device for a vehicle seat, comprising: right and left frame members by which the vehicle seat can be supported and which extend in a front-and-rear direction, front attachment portions and rear attachment portions located in each of front portions of the right and left frame members and in each of rear portions of the right and left frame members, respectively, each of the front and rear attachment portions being attachable to a load sensor, and the front portions and the rear portions of the right and left frame members, in which the front attachment portions and the rear attachment portions are formed respectively, are wider in a right-and-left direction than middle portions of the right and left frame members, the middle portion of each of the right and left frame members being defined between the front portion and the rear portion of each of the right and left frame members, respectively, and the right-and-left direction being perpendicular to the front-and-rear direction.
 2. The passenger weight measurement device as claimed in claim 1, wherein the front attachment portions and the rear attachment portions are formed in each of extending portions respectively, which extend from the right and left frame members respectively in the right direction or the left direction.
 3. The passenger weight measurement device as claimed in claim 2, wherein the extending portion in which the front attachment portion of one frame member of the right and left frame members is formed and the extending portion in which the rear attachment portion of the one frame member is formed, extend in a same direction.
 4. The passenger weight measurement device as claimed in claim 2, wherein the extending portion in which the front attachment portion of one frame member of the right and left frame members is formed, extends in one direction of the right direction and the left direction, and the extending portion in which the front attachment portion of the other frame member of the right and left frame members is formed, extends in an opposite direction to the one direction.
 5. The passenger weight measurement device as claimed in claim 2, wherein the extending portion in which the front attachment portion of at least one frame member of the right and left frame members is formed, is wider in the front-and-rear direction than the extending portion in which the rear attachment portion of the one frame member is formed.
 6. The passenger weight measurement device as claimed in claim 2, wherein the extending portion in which the front attachment portion of at least one frame member of the right and left frame members is formed, comprises an edge part which extends in an extending direction and a base part, and wherein the edge part is narrower in the front-and-rear direction than the base part.
 7. The passenger weight measurement device as claimed in claim 2, wherein an upper surface of the extending portion in which the front attachment portion of at least one frame member of the right and left frame members is formed, is larger than an upper surface of the extending portion in which the rear attachment portion of the one frame member is formed.
 8. The passenger weight measurement device as claimed in claim 2, wherein the extending portions in which the front attachment portions of the right and left frame members are formed respectively, are wider in the front-and-rear direction than the extending portions in which the rear attachment portions of the right and left frame members are formed respectively.
 9. The passenger weight measurement device as claimed in claim 2, wherein upper surfaces of the extending portions in which the front attachment portions of the right and left frame members are formed respectively, are larger than upper surfaces of the extending portions in which the rear attachment portions of the right and left frame members are formed respectively.
 10. The passenger weight measurement device as claimed in claim 2, wherein a projecting part which projects upwardly is formed on the extending portion.
 11. The passenger weight measurement device as claimed in claim 10, wherein the projecting part is formed so as to enclose the load sensor.
 12. The passenger weight measurement device as claimed in claim 10, wherein the projecting part is formed in a substantial U-shape as viewed from above so as to enclose the load sensor.
 13. The passenger weight measurement device as claimed in claim 12, wherein the projecting part formed in the substantial U-shape is continuous.
 14. A passenger weight measurement device for a vehicle seat, comprising: right and left frame members by which the vehicle seat can be supported and which extend in a front-and-rear direction, front attachment portions and rear attachment portions located in each of front portions of the right and left frame members and in each of rear portions of the right and left frame members, respectively, each of the front and rear attachment portions being attachable to a load sensor, and each of the right and left frame members has a concave portion located between the front attachment portion and the rear attachment portion.
 15. The passenger weight measurement device as claimed in claim 14, wherein the concave portion is provided on an outer surface of each of the right and left frame members.
 16. The passenger weight measurement device as claimed in claim 14, wherein the concave portion is provided in a position opposite to each of right and left attachment base members which are attached to a vehicle side and which extend in the front-and-rear direction.
 17. The passenger weight measurement device as claimed in claim 16, wherein each of the right and left attachment base members comprises a fixed rail fixed to the vehicle side and a movable rail disposed to be movable in the front-and-rear direction on the fixed rail.
 18. The passenger weight measurement device as claimed in claim 14, wherein a first connecting member for connecting the right and left frame members is provided on a rear side of the concave portion.
 19. The passenger weight measurement device as claimed in claim 18, wherein the first connecting member is directly connected with the rear attachment portions of the right and left frame members.
 20. The passenger weight measurement device as claimed in claim 14, wherein a second connecting member for connecting the right and left frame members is provided on a front side of the concave portion.
 21. The passenger weight measurement device as claimed in claim 20, wherein the second connecting member is directly connected with the front attachment portions of the right and left frame members.
 22. The passenger weight measurement device as claimed in claim 20, wherein a bent portion is formed in each of both end portions of the second connecting member.
 23. The passenger weight measurement device as claimed in claim 17, wherein a third connecting member for connecting the right and left attachment base members is provided at a position opposite to each concave portion.
 24. The passenger weight measurement device as claimed in claim 14, wherein an elongated hole which is elongated in the front-and-rear direction is formed in at least one of the right and left frame members in which the concave portion is formed and the elongated hole is provided in a position opposite to the concave portion.
 25. The passenger weight measurement device as claimed in claim 17, further comprising a lock mechanism for locking each movable rail of the attachment base members to each fixed rail of the attachment base members, and each of both end portions of an operating lever member for releasing a locking condition of the movable rails and each of the front attachment portions are arranged in the front-and-rear direction along each of the attachment base members.
 26. The passenger weight measurement device as claimed in claim 1, further comprising right and left attachment base members including a fixed rail fixed to a vehicle side and a movable rail disposed to be movable in the front-and-rear direction on the fixed rail, and the passenger weight measurement device further comprises a lock mechanism for locking each movable rail of the attachment base members to each fixed rail of the attachment base members, and each of both end portions of an operating lever member for releasing a locking condition of the movable rails and each of the front attachment portions are arranged in the front-and-rear direction along each of the attachment base members.
 27. A passenger weight measurement device for a vehicle seat, comprising: right and left rail members, each of the rail members comprising a fixed rail fixed to a vehicle side and a movable rail disposed to be movable in a front-and-rear direction on the fixed rail; and right and left frame members which are provided on the right and left rail members, respectively, and which extend in the front-and-rear direction along the right and left rail members, front attachment portions and rear attachment portions located in each of front portions of the right and left frame members and in each of rear portions of the right and left frame members, respectively, each of the front and rear attachment portions being attachable to a load sensor, the front portions and the rear portions of the right and left frame members, in which the front attachment portions and the rear attachment portions are formed respectively, are wider in a right-and-left direction than middle portions of the right and left frame members, the middle portion of each of the right and left frame members being defined between the front portion and the rear portion of each of the right and left frame members, respectively, and the front attachment portions and the rear attachment portions are formed in each of extending portions respectively, which extend from the right and left frame members respectively in a right direction or a left direction, the right-and-left direction being perpendicular to the front-and-rear direction, the extending portion in which the front attachment portion of one frame member of the right and left frame members is formed and the extending portion in which the rear attachment portion of the one frame member is formed, extend in a same direction, each of the right and left frame members is connected respectively to each of right and left side frames on a side of the right and left frame member from which each of the extending portions extends, and each of the right and left side frames is connected on each surface of the right and left frame members, the surface being opposite to a side on which the load sensors are provided.
 28. The passenger weight measurement device as claimed in claim 27, further comprising a pan frame for connecting front side frame portions of the right and left side frames, a spring is attached to the pan frame, and the front attachment portions and the rear attachment portions are provided on an outer side of the spring.
 29. The passenger weight measurement device as claimed in claim 28, further comprising a first connecting member for connecting the rear attachment portions of the right and left frame members, and wherein a backseat frame is connected to the right and left side frames backward of the first connecting member and above the first connecting member.
 30. The passenger weight measurement device as claimed in claim 27, wherein the extending portion in which the front attachment portion of at least one frame member of the right and left frame members is formed, is wider in the front-and-rear direction than the extending portion in which the rear attachment portion of the one frame member is formed.
 31. The passenger weight measurement device as claimed in claim 27, wherein a projecting part which projects upwardly is formed on the extending portion.
 32. The passenger weight measurement device as claimed in claim 31, wherein the projecting part is formed so as to enclose the load sensor.
 33. The passenger weight measurement device as claimed in claim 27, wherein the extending portion in which the front attachment portion of one frame member of the right and left frame members is formed, extends in one direction of the right direction and the left direction, and the extending portion in which the front attachment portion of the other frame member of the right and left frame members is formed, extends in an opposite direction to the one direction.
 34. A passenger weight measurement device for a vehicle seat, comprising: right and left frame members by which the vehicle seat can be supported and which extend in a front-and-rear direction, front attachment portions and rear attachment portions located in each of front portions of the right and left frame members and in each of rear portions of the right and left frame members, respectively, and the front portions and the rear portions of the right and left frame members, in which the front attachment portions and the rear attachment portions are formed respectively, are wider in a right-and-left direction than middle portions of the right and left frame members, the middle portion of each of the right and left frame members being defined between the front portion and the rear portion of each of the right and left frame members, respectively, and the right-and-left direction being perpendicular to the front-and-rear direction.
 35. The passenger weight measurement device as claimed in claim 34, wherein the front attachment portions and the rear attachment portions are formed in each of extending portions respectively, which extend from the right and left frame members respectively in the right direction or the left direction.
 36. The passenger weight measurement device as claimed in claim 35, wherein the extending portion in which the front attachment portion of at least one frame member of the right and left frame members is formed, is wider in the front-and-rear direction than the extending portion in which the rear attachment portion of the one frame member is formed.
 37. The passenger weight measurement device as claimed in claim 35, wherein a projecting part which projects upwardly is formed on the extending portion. 